Paper manufacture



Oct. 20, 1942.

H. e. CHATAIN ETAL PAPER MANUFACTURE Filed March 15, 1940 3 Sheets-Sheet 1 INVENTORS Henri G. Ckatam amt firberz L.Dyr Jr. 50. gm

ATTORNEY 1942. H. G. CHATAIN ETAL PAPER MANUFACTURE 3 Sheets-Sheet 2 Filed "March 16, 1940 (SCEQ ATTO R N EY 1942' H. s. CHATAINQ ETAL 7 2,

PAPER MANUFACTURE Filed March 16, 1940 3 Sheets-Sheet 3 INVENTORS Henri (1' Chalaz'n and lferbert L .DyerJP:

ATTORNEY Patented Oct. 20, 1942 OFFICE PAPER MANUFACTURE Henri G. Chatain and Herbert L. D er, Jr., Erie, Pa., assignors to Hammer-mill Paper Company, Erie, Pa., a corporation of Pennsylvania Application March 16, 1940, Serial No. 324,284

8 Claims.

This invention relates to the paper manufacture and has for one of its objects the provision of new and improved means for facilitating the drying of the paper in the dryer sections of paper machines. In this connection the invention provides a novel and advantageous means for :drying the felt bands which are commonly employed to press the paper web into engagement with the dryer rolls. It further provides novel means, supplemental to the main or primary dryers, for directing air currents upon the paper on said dryers to accelerate the drying of the paper.

' The present embodiment is illustrated in connection with the invention disclosed in an application of H. G. Chatain, filed concurrently herewith, Tin which undesirable shrinking and curling of the paper web is obviated by the maintaining of a substantially saturated dead-air space in the central zone of the dryer section. While the present invention. is especially advantageous for expediting the drying of the paper in conjunction with apparatus wherein substantial drying does not take place in the aforementioned central zone, as disclosed in said Chatain application,

and while the combination of said drying provisions with the prevention of drying in said central zone constitutes a distinctly useful phase of our invention, it will nevertheless be apparent that the utility of the felt drying means and the supplemental paper drying provisions of the invention are not restricted to said combination and that they may be employed wherever acceleration of the rate of drying is desired.

Other features and advantages of the invention will be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a vertical sectional view, with parts in elevation, illustrating an embodiment of our invention.

Fig.2 is a horizontal sectional view taken approximately on line 2-2 of Fig. 1.

Fig. 3 is a transverse vertical sectional view, taken approximately on line 3-3 of Fig. 1.

Fig. 4 is a fragmentary sectional view of a detail.

Referring to the drawings, there is shown a dryer section of a paper machine, said dryer section including the usual upper and lower sets of dryer rolls. The numerals I, 3, 5, l and 9 designate dryer rolls in the upper set, while numerals 2, 4, 6, 8 and Ill refer to dryer rolls in the lower set. Said rolls may be supplied with steam in the customary way through pipes l' and may be driven through gears 2' in any suitable or conventional manner to advance the web of paper I I through the dryer section in the direction indicated by the arrow II. Overlying the paper in its passage over the upperrollers is the usual endless felt band l2 which passes over suitable rollers, such as are indicated at l3 and the lower course of which travels in the same direction as the paper and presses the latter firmly against said upper dryer rolls. Conventional tension regulating apparatus for the felt band I2 is indicated at ll.

Similarly an endless felt band l5 passes over the usual rollers l6 and tension regulating means ll in the lower part of the dryer section, the upper course of which band travels in the same direction as the paper and maintains the latter pressed firmly against the lower drying rolls.

The various rolls may be mounted in suitable main side frames A and B (Fig. 3), each of which side frames may comprise a series of lower pedestals, such as indicated at l9a,- I91), and l9c, which pedestals are connected by beam 20. The lower dryer rolls may be journaled in bearings 2| on the beams 20. Supported on each of said beams is a series of upwardly extending pedestals, such as indicated at 22a, 22c and 22d, carrying bearings 23 at their upper ends, in which bearings the upper dryer rolls are journaled. Ifhe last mentioned series of pedestals are interconnected by frame elements, such as are indicated various pedestals and beams may be secured together in any suitable way, as by bolts or welding. A housing 29 of sheet metal or other material is mounted, through inwardly projecting exten-' sions 29', on flanges of the beams 26a--26e, as indicated in Fig. 3, and serves to enclose the top of the dryer section. At the front nd rear sides of the lower portion of said dryer section there are provided suitable plates or frames 30 and 3|, respectively, each having a flange 30', -3l', projecting into engagement with a flange of the adjacent beam 20, said frames extending to the bottom of said section. The flanged portion 3| of frame 3| may be pocketed as shown at 3|" in Fig. 3 to accommodate the gears for driving the respective lower dryer rolls. Similarly the flanged rear portion of housing 29 may be pocketed, as indicated at 29", to accommodate the gears for.driving the respective upper dryer rolls.

For maintaining the air in the central zone of the dryer section (1. e., the zone in which the paper passes between the upper and lower drying 1 portions of said section. Such means, as shown,

, may take the form which is disclosed in the ,said rearside and suitably secured at its top to the housing 29 and at its bottom to the plate 3|. At the front, the exterior air may be excluded by a series of curtains 34 (Figures 2 and 3) mounted on rollers 36 in suitable brackets 36'. Each curtain may contain a window of flexible transparent material so that the operator may look into the interior of the dryer section without raising the curtain, as shown in said Chatain application.

As illustrated in Figure 2, each curtain may be mounted between adjacent beam elements 31, of T-shaped cross section, which elements extend from top to bottom of the machine, and to which elements said brackets 36' are welded or otherwise suitably secured. Said beam elements 31 also serve as reinforcing members, in which connection it will be noted that the frame or plate 30 may consist of sections secured to said beam elements, as by bolts or through welding, and extending therebetwen. Similarly the front wall of the housing 29 may comprise sections 29a extending between said beam elements 31 and suitably fastened thereto.

It has been previously noted that the lower course of the felt band l2 travels in the same direction as the paper through the dryer sections, i. e., in the direction of the arrow II, and presses the paper firmly against the upper dryer rolls. As shown in Figures 1 and 2," said felt passes around the upper half of the circumference of each of said rolls and also passes under guide rolls 39 positioned between said dryer rolls. Said felt also is of such width as to extend over substantially the entire length of each of-"the aforesaid rolls.

Between the ends of the upper dryer rolls and the respective side frames A- and B, shields 40, 4| are provided for blocking substantially any interchange of air between the aforementioned central and upper zones around the ends of said rolls. Since said shields 40 and 4| may be substantial duplicates, a description of shield 40 will suffice. I

Said shield 40 may be of metal and, as shown,

may be curved to conform with the curvature of the dryer rolls. Said shield may" conveniently be formed in sections Ia-40c each of which may be formed integrally with a corresponding one of the beam sections 26a26e, and also with a corresponding one of the frame elements 24a--24e. Between adjacent dryer rolls, each of the shield sections comprises a portion 40' which passes under the corresponding guide roller 19 and is provided with a bearing portion 42 for the adjacent journal 39' of said roller, as shown in Figures 1 and 3. Each of the frame sections 24a--24e'may have a flange 44 projecting from the bottom web 24 thereof and merging with Y provides for substantiallyisolating the air in the the associated bearing portion 42 to impart additional rigidity thereto. Each of the shield sections may be also provided with a web 43 extending upwardly from the aforementioned portion 40' and merging with the lower flange 44 of the corresponding one of the frame elements (z-24c, and also merging with the aforesaid bearing portion 42. If desired, each of the 55 48 may be formed inlike manner.

with its associated frame element 24a24e, and the corresponding shield section may be cast integrally with said beam section and associated frame element, or the corresponding sections and 5 elements may be formed separately and welded or otherwise secured together.

It will be seen that the above mentioned shield sections follow substantially the course of the low run of the felt I2 and extend between the adjacent edge of said felt and the frame A. As

above noted, the shield 4| between the opposite edge'of the felt and the frame B may be constructedof sections arranged in the same manner as described in connection with the shield 40. In the drawings, the sections of shield 4| are designated 4 111-4 le, respectively.

Since the air in the above mentioned central zone cannot pass upwardly through the dryer and guide rolls aforementionedor through the felt I2 which extends over substantially the em tire lengths of said rolls and passes betweenthe dryer rolls, and since said air also cannot pass upwardly through the shields 40 and 4| interposed between said rolls and the side frames, it

will be apparent that the air in said central zone is substantially isolated from that in the upper ,portion of the machine.

' The upper course of the felt l5, as previously observed, runs in the same direction as that in at) which the paper travels through the machine and presses the paper firmly against the lower dryer rolls. Said felt passes around the lower half of the circumference of each of said lower dryer rolls and also over guide rolls 46 journaled in the pedestals 220-2211 of the side frames. In

addition, said felt is of such width as to extend substantially across the full length of said dryer and guide rolls. Shields .41 and 48, similar to the shields 40 and 4|, are interposed between the 40 ends of the lower dryer rolls and the respective aside frames A and B for blocking substantially any interchange of air between the central and lower zones around the ends of said rolls.

l teferring ,to Figures 1 and 3, it will be seen that the shield 41 may be formed in sections cast integrally with or otherwise united tothe side frame A. As shown, said shield comprises sections 41a, 41b, 41c, 41d, and 41e, united to the beam 2|! and to respective pedestals such as |9a-|9c, as well as to reinforcing webs IS integral with said beams and pedestals. Said shield also comprises intermediate sections 41,, 41g, 41h, and 411, cast integrally with or otherwise secured to the respective pedestals 22a.--22d. The shield The guide rollers 46 for the upper run of thefelt band l5 may be journaled for rotation in the pedestals fizz-22d as previously noted; and the shield 41, 48 are arranged as shown, to follow 0 the course of the felt and to pass above said rollers. The air in the central zone aforesaid cannot pass downwardly through the lower dryer and guide rolls or through the felt into the lower zone of the machine, nor can it pass through the o5 shields into said lower zone.

It will thus be evident that the foregoing means of said section, as well as from the outside air.

'As a result, when the machine is set into operation, said air in the central zone will speedily' become saturated with moisture to such extent as to be unable to absorb any substantial amount of beam sections mic-26c may be cast integrally i5 moisture from the p p passing between the upper and lower sets of drying rolls, and drying of the paper will be substantially prevented in said central zone. Thus, the drying of the paper will be practically entirely restricted to the dryer rolls, on which the paper is held from shrinking or curling, and the conditions which give rise to curling and shrinking are obviated. I

Whil a slight interchange of air may take place between said central zone and the zones above and below the same, since a small space exists between the edges of the shields and the ends of the dryer rolls, no more than a small interchange of air can take place-between said zones, so that the central zone is substantially isolated from said upper and lowerzones. Preferably, complete elimination of drying is not obtained in said central zone, because some small shrinkage is desirable to prevent slack of the paper from manifesting itself at some point. The provisions hereinbefore described enable the pre-' vention of drying in said central zone to the extent desired and without preventing some slight drying therein sufllcient for preventing the occurrence of slack. The space between said shields and the ends of the drier rolls may be so chosen as to achieve the desired extent of prevention of drying in the central zone. "It is preferred to eliminate'all drying in that zone except for the very small amount desirable for preventing slack.

In starting the machine, or in case of a "break," the operator may. raise one or more of the curtains I. to obtain greater accessibility.

It may be observed that while the central zone of the dryer section is, of course, open at opposite ends, exterior air cannot enter said central zone from either end to any substantial extent, since the web of paper passes across said central zone between the upper and lower sets of paper dryer rolls, and said web is of such width as to extend over substantially the entire lengths of said rolls.

As above noted, the foregoing means for substantially isolating the air in the central zone from the outside air as well as from the air in the upper and lower zones of the dryer section is disclosed in the. aforementioned Chatain application; and said means is not claimed hereinper se, since it is the-sole invention of said H. G. Chatain.

As further pointed out in said Chatain application, it is desirable to provide for facilitating the drying of the paper in the upper and lower zones of the dryer section. to whic rolls may be provided in moisture from the felt, moisture from the paper.

In this connection we provide dryer rolls for the felt bands so coordinated with said Bands as to enable the inclusion of as many of said rolls as desired while at the same time maintaining the paper dryer rolls closely adjacent each other. More particularly, as illustrated in connection with the felt band II, we have shown dryer rolls SI for said band, which may be supplied with steam through pipes 50' in the same" manner as the paper dryer rolls, and which may be mounted in bearings 21 on the beam sections 26a, 26b, etc. As shown. each roll 50 is mounted above a guide roller 39. In addition, below each roll 50, and above the corresponding roller 39, there is provided between adjacent paper dryer rolls another guide roller ll.

The aforesaid rollers 39 and SI guide the felt in its passage to and from the corresponding-roll 50. Thus, for example, as shown in Fig. l, the felt, after passing over the paper on the dryer roll I,

h end suitable drying said zones for extracting which in turn absorbs 0 able manner,

passes around the adjacent guide roller 5 I, thence over the associated felt dryer roll Ill, then around guide roller 39, and then over the paper on the succeeding dryer roll 3. The guide rollers Il may be journaled in various ones of the frameelements 24a, 24b, etc. a

I It will be seen that the above-described arrangement of felt dryer rolls and guide rollers, with roller 5| above the roller 8!, enables the paper dryer rolls to be maintained in closely adjacent relation to each other, and furthermore permits as many felt dryer rolls 5! to be employed as desired without disturbing the compact arrangement of the paper dryerrolls.

Likewise, in the lower zone of the dryer section, we provide steam-heated dryer rolls for the felt band It, one of which dryer rolls is indicated at 53, mounted in bearings in pedestals 54. The previously mentioned guide rollers 46, as well as other guide rollers 56 positioned below the respective'rollers 46 and above the rolls 5!, guide the felt band I! to and from said rolls 53. Thus, for example, the felt passing from the paper on the roll 2 proceeds around the adjacent guide roller 56, thence around the associated dryer roll 53, and then around a guide roller 46 from which it passes on to the paper on the succeeding paper dryer roll 4. Guiderollers 58 may be journaled in the side-frame beams 20, as indicated in Fig. 1.

The housing 29 for the upper zone of the dryer 1 section abov noted, is preferably connected at the dry en to a system of ducts and pressure fans such as toreceive a measured supply of heated air under a slight pressur The capacity of the zone is such as to contain a sumcient amount of air for drying purposes so that the said air will under all conditions be exhausted at the opposite or wet end of the zone withthe saturation desired. The air travels through said zone, counter-current to the travel of the paper and felt toward the wet end of the drier section. Fans 52,, mounted at convenient points in said housing, may be provided to direct currents of air back and forth across the machine and over exposed surfaces of the felt I! to assist in removing water vapor therefrom. Thus the air in said housing not only travels counter-current toward the wet endof the machine but is furthermore circulated back and forth across the machine by the fans 52, as the result of which the air becomes progressively wetter until at the wet end of the machine it becomes saturated to a desired extent, preferably to such extent as to be no longer suitable for drying purposes. The wet air may then be exhausted to atmosphere or conducted to a suitable heat reclamation system. In addition, to being heated, the air supplied to said housing 29 may be conditioned in any suittb lower its moisture content to a desired value prior to its introduction into said housing.

The housing" for the lower zone of the dryer section jlike that heretofore described for the upper zone, is preferably connected at the dry end to a system of ducts and pressure fans for receiving a measured quantity of heated and humidity-conditioned air under slight pressure,

andi'ans'il may be provided in said lower zone to direct currents of said air back and forth fiac'r'oss the machine and over exposed portions of the felt I! to promote the drying thereof. In the lower, as in the upper, housing the air travels counter-current to the paper and felt, and becomes progressively wetter, emerging at the wet end either to atmosphere or to a heat reclamation system.

The aforementioned provisions for drying the felt bands l2 and also, of course, facilitate the drying of the paper in contact with the felt. As many dryer rolls 58 and 53 may be provided as desired.

To accelerate further the drying of the paper, we have provided supplemental paper drying rolls 58, which may be included in the upper and lower zones aforesaid in close proximity to certain of the main dryer rolls. As shown more particularly in Figures 3 and 4, each of these dryer rolls is provided with apertures or perforations 58 in its cylindrical wall and has an open end into which there extends afan 68. The other end of each of said rolls is closed by a. member 58' (Figures 3 and 4) which carries a journal 58". in the upper zone and two in the lower, but it Two of said rolls 58 are shown will be understood that any desired number of said rolls may be provided in each zone.

In the upper zone, as shown in Figures 1 and 2, each roll 58 is journaled at one end in pedestal 28, on one of the beam sections of the series 28a-26e, and at its opposite or open end is rotatably mounted on rollers Si in a frame 28' secured to the corresponding beam section of the opposite side frame.

As shown in Figures 1 and 3, each of the rolls 58 in the lower zone may be iournaled at one end in aggearing 82 extending from one of the series of destals l8al8c of the associated side frame. At its open end each of said rolls in the lower zone is rotatably mounted on rollers, such as indicated at 63 and 84, supported by the corresponding pedestal of the adjacent side frame and by the associated web l8.

Adjacent each of the upper supplemental dryer rolls 58 is a guide roller 85 journaled in pedestals on appropriate ones of the series of beam sections ,28a28e. The felt from the associated main dryer roll passes under the roller 85, thence over the supplemental roll 58, then downwardly into engagement with the paper on said main dryer roll, vand thence under the associated guide roller 39, as shown in Fig. 1. Likewise, guide rollers 88, journaled in pedestals l8b and I80 are alsoshown in conjunction with the lower supplemental dryer rolls; the felt from the corresponding lower main dryer rolls being passed over said guide rollers, thence over said supplemental dryer rolls, then upwardly into engagement with the paper on said main dryer rolls, and

thence over the associated guide rollers 46.

It will thus be seen that adjacent each of the supplemental dryer rolls 58 the felt is removed from engagement with the paper on the associated main dryer roll to expose said paper to the.

action of the air blown through the perforations 58 by the fan 88. The rate of drying of the paper is thereby particularly accelerated.

It is preferred that the perforations or apertures 58 be inclined at an angle of about fortyflve degrees, as shown in Fig. 4, to direct the air on to the paper at that angle. The fiow of air against the paper at such an angle continuously dispels the film of saturated airin contact with the paper and replaces it with fresh air which strikes the paper and removes moisture therefrom in an especially efficient manner. In addition, the direction from which the air from the apertures side of the machine away from the side from which air enters the roll 58 containing said apertures, as will be readily apparent from Fig. 4.

It will be noted that the successive rolls 58 in the upper zone are arranged with their open ends and fans 88 on opposite sides of the machine, to avoid any drying unbalance which might otherwise occur across the sheet due to the unidirectional discharge of the moistureladen air from any one roll. Likewise, the successive rolls 58 in the lower zone are arranged to take air from opposite sides of the machine, for the same reason.

When the paper first comes into the dryer section it is quite cool and wet, and paper making technique demands that the sheet temperature be raised gradually to minimize tendencies to cockle. Evaporation at this stage is quite limited with the conventional arrangement of felts and dryercylinders. The felt dryer rolls 58, 53 are preferably located in the region adjacent the forward or wet end of the dryer section, in which region the dryer felts are capable of blotting up considerable moisture from the damp paper sheet. This moisture is immediately driven out of the felt by means of the felt dryer rolls, whereby the subsequent paper drying rolls may be used for the sole purpose of drying the paper without the necessity of also having to drythe felt. It is preferred that the felt dryer rolls bemaintained at 'a temperatureconsiderably higher than that of the first few paper dryer rolls, to expedite the driving of moisture from the felts.

The supplemental drying rolls 58 are preferably provided in the region following that in which the combined blotting and felt-drying action above described can be employed to good advantage. At the end of the felt-drying region the paper sheet has been brought up to its normal drying temperature, and it is in the succeeding region that the aforementioned supplemental drying rolls 58 are preferably located. The air directed on to the paper from said supplemental rolls subjects the paper to a uniform drying action across the full width of its surface.

While the paper opposite the supplemental dryer rolls 58 is not engaged by the felt, said paper is held against shrinkage by its adhesion to the main drier rolls. It is preferred that said supplemental drier rolls be discontinued at the point in the drier section where the paper surface has become dried to such extent that the influence of air currents across said surface has no substantial effect on the drying rate. The discontinuance of said supplemental rolls at that point is furthermore desirable since when that stage of drying is reached the ability of the paper sheet to cling to the surface of the main dryer rolls has been materially lessened. From that point on to the end of the dryer section the drying is primarily a question of the rate at which moisture in the interior of the sheet can be driven to the surface. The agent best suited for this purpose is heat. Hence, in the portion of the dryer section following said supplemental rolls 58 the drying can be effectively accomplished by the main dryer rolls against which the paper is firmly pressed by the felts. In the drawings, only a portion of the dryer section is shown, for purposes ofillustration, but it will be understood that the rolls 58 are preferably not provided beyond the point indicated, and that from that point on to thedry or rearward end of the dryer section the sheet is held on the main dryer rolls by the felts, and is dried by said I in the customary manner.

It will be seen from the foregoing description that the invention provides for the particularly expeditious production of paper having superior characteristics, free from the objectionable rough edges and curling tendencies previously encounrolls tered, and additionally enables the speed of pro-' duction to be markedly increased. Even without increase in speed of operation, a greater quantity of paper may be produced and at a reductionin cost, since time and expense are saved by the reduction of broke which, must be dried for remanufacture, the full deckle width of the machine is at all times available, and an increase in reel width is achieved due to marked decrease in crosswise shrinkage of the sheet. While these increases in production are attainable without rise in speed of operation, the invention further, as above noted, provides for increased capacity at higher speeds. And this increased capacity is obtained without the need of lengthening the dryer section. I

The terms and expressions which we have employed are used as terms of description and not paper on said roll and for directing air on to a portion of the paper on said roll for accelerating drying of the paper.

4. Paper drying apparatus comprising drying rolls over which a Web of paper passes, an absorbent band passing over said rolls and engaging portions of the paper thereon supplemental drying means comprising a perforated member positioned between said band and one of said rolls, said member being arranged to support and separate said. band from said roll, and means for causing an air current to pass through the perforations in said member and on to the paper on said roll.

5. Apparatus for drying a sheet of paper passing over drying rolls in the dryer section of a paper machine, said apparatus comprising a flexible band adapted to engage the paper on one side and to establish intimate contact between the other side of said paper and the surface of a .dryer roll; means comprising a perforated memof limitation, and we have no intention,-in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible Within the scope of the invention claimed.

We claim:

1. Paper drying apparatus comprising an upper set of drying rolls and a lower set of drying rolls around which a web of paper passes, means for substantially isolating the air in the zone wherein the paper is out of contact with said rolls while it passes from one set of rolls to.the other to prevent substantial drying of the paper in said zone, bands of absorbent material passing over the rolls of the respective sets and engaging portions of the paper on said rolls, means for applying heat to said hands for extracting moisture therefrom, and means located adjacent certain of said rolls for supporting and separating the bands from the paper on the last mentioned rolls and for directing air on to the paper on said last mentioned rolls for facilitating the drying thereof.

2. Paper drying apparatus comprising an upper set of drying rolls and a lower set of. drying rolls around which a web of paper passes, means for substantially isolating the air in the zone wherein the paper is out of contact with said rolls while it passes from one set of rolls to the other to prevent substantial drying of the paper in said zone, bands of absorbent material passing over the rolls of the respective sets and engaging portions of the paper on said rolls, and means located adjacent certain of said rolls and interposed beflween said bands and the last mentioned rolls for supporting and separating said bands from the paper on said rolls and directing air on to portions of the paper on said rolls for accelerating drying of the paper.

3. Paper drying apparatus comprising drying rollsover which a web of paper passes, an absorbent band passing over said rolls and engaging portions of the paper thereon, and means interposed between-said band and one of said rolls for supporting and separating said'band from the stantial drying of he paper in said zone, and acher positioned adjacent to said dryer roll and adapted to remove said flexible band from contact with said paper, thereby exposing a surface of said paper and subsequently to return said band to contact said paper while said paper is still in intimate contact with said dryer roll, and means for directing air currents through the perforations in said perforated member on to said exposed surface of said paper.

6. The method of drying paper in the dryer section of a paper machine in which the paper ispassed over a series of dryer rolls, said method comprising pressing one side of the paper sheet against the surface of a dryer roll during its passage thereover by contacting the other side of paper sheet with-a flexible band; removing band from contact with said paper by passan element adjacent to "said dryer roll thereby exposing a surface of said paper; returning said band into contact with said paper while said paper is still in intimate contact.

with said dryer rolls; and directing an air current on to said exposed surface of said paper.

7. The method of controlling the drying of paper passing through upper and lower sets of dryer rolls in a paper machine, said method comprising preventing substantial escape of air from the zone intermediate the upper and lower sets of dryer rolls to thereby maintain in contact with the portions of the paper passing between said rolls a substantially isolated mass of humid air to prevent substantial drying of the paper in said zone,-and accelerating the drying of the paper by directing currents of air upon certain of the portions of the paper in contact with said rolls.

8. The method of controlling the drying of paper engaged by absorbent bands and passing through upper and lower sets of dryer rolls in a paper machine; said method comprising preventing substantial escape of air from the zone intermediate the upper and lower sets of dryer rolls to thereby maintain in contact with the portions of the paper passing between said rolls a substantially isolated mass of humid air to prevent sub- -celering the drying of said paper by directing air currents between said bands and portions of the paper on certain of said rolls. Y

HENRI G. CHATAIN. HERBERT L. DYE'R, JR. 

